Terumo BCT Trima Accel, Service Manual

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The motor driver CCA monitors the power to the lock solenoid for problems. If there is an under-
voltage or over-current problem, it sends a solenoid fault bit (1=normal, 0=fault) to the control
CCA. This fault is logged in the STS fault screen.
Door Lock Assembly (Lock Solenoid and Optical Door Position Sensor)
The lock solenoid is magnetically latching, which means that when the shaft is pulled into the lock
solenoid, it is held there by magnetic force (shaft in), which overcomes the spring force that holds
the shaft in the locked position (shaft out). There is an access hole that can be used to push in the
locking shaft to manually unlock the door if power is lost.
The locking shaft has an attached flag that triggers the optical solenoid position sensor. The optical
sensor sends its output to both control and safety CCAs (an alarm is generated if these two do not
agree). In the unlocked position, the IR light is blocked by the flag, sending a “1” bit to both
control and safety CCAs; in the locked position, the IR light shines through a hole in the flag,
sending a “0” bit to both systems.
The door position optical sensor is activated by a flag attached to a plunger that moves to trigger
the sensor when the door latch plate moves the plunger. In the open position, the IR light is
blocked by the flag, sending a “1” bit to just the safety system; in the closed position, the IR light
shines through a hole in the flag, sending a “0” bit to safety only (because the other set of door-
position data is from the Hall-effect sensor on the other side of the door).
Hall-Effect Door Position Sensor
The Hall-effect door position sensor is on the left (IV pole button) side of the device. This is one of
two door position sensors, one on each side of the device, used for redundancy and to help indicate
when the door has not closed evenly. On the left (IV pole button) side is the Hall-effect sensor, and
on the right (power switch) side is the optical sensor.
The south-pole side of a magnet in the latch plate triggers the feedback signal. When the door is
closed, the magnet is detected and the sensor outputs a “1” bit to the control CCA. When the door
is open, the magnet is not detected and the sensor outputs a “0” bit. The sensor is powered by 5 V
that comes from a different source than the LED light voltage in the optical sensors (because of the
LED test that occurs every 60 seconds).
Control CCA (End)
The control CCA receives the feedback position bits from the locking shaft position sensor and the
door position Hall-effect sensor. The shaft position sensor gets split and goes to both the control
and safety CCAs. The control CCA reports these two items to the control computer only.
The control and safety systems are both looking for the position sensor bit to confirm the position
of the locking shaft. They must both agree on the position, or an alarm is generated. As a
redundant safety mechanism, the control CCA is monitoring one half of the door position output
(Hall-effect) and sends this data to the control computer. The safety CCA is monitoring the other
half of the door position output (optical) and sends this data to the safety computer. The two
computers compare this data through an Ethernet connection, and the two sets of sensor data
must agree, or an alarm is generated.
Door System
Trima Accel
®
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